1. Field of the Invention
These inventions relate to perimeter and frame rail elements and assemblies for display cases.
2. Related Art
Commercial refrigerators and refrigerated display cases (coolers and freezers) are used in markets, food-vending operations, liquor stores and the like for the preservation of freshness and attractive display of product to the customer. Typically, commercial display cases have extruded aluminum frames defining a rectangular opening for the case which is accessed through sliding doors or swing doors having large areas of multi-layered glazing to permit the customer to see, select and access the refrigerated product easily, while preventing heat transfer into the refrigerated space. The raw aluminum is expensive and the extrusion process also adds significant costs to the final product. After extrusion, the linear segments of rail are cut to the desired length and shape (such as to have mitered corners), punched to give holes for mounting and fastening various hardware to the frame rail, and finished to remove rough edges and the like. Four frame rail elements are used for small to medium-sized cases while more may be used for larger cases. The frame rails are fastened together at mitered corners of upper and lower horizontal frame members and left and right vertical side members, sometimes referred to as end mullions. The surrounding frame rails typically have a decorator strip, extending over the front of the case, a side-wall extending inwardly relative to the case from the decorator strip, the side-walls of the top and bottom rails supporting the hinges for the doors, and a transverse wall for mounting a contact plate against which the magnetic gasket on the door seals. The transverse wall also forms a support for center mullions in the display case. The center mullions extend vertically between upper and lower frame rails to give a sealing surface for the doors and contain wiring, ballasts or other hardware for operating lighting units mounted on the surfaces of the mullion extending into the display case. The rearwardly facing portions of the transverse walls also may support raceways or other hardware for equipment used in the unit.
The hardware for connecting the corners of the frame rail structures, and for connecting the mullions and the frame rail elements, can be complicated, with a significant number of inter-fitting parts to provide a suitable corner connection. Additionally, the processing of the frame rail elements that permits hardware such as hinges and hold opens to be mounted to the frame uses multiple steps and adds to the cost of the final product.
Typically, an extruded aluminum door rail supports and surrounds the multi-layered glazing to support the glazing panels and to protect the edges thereof. Such door rails hold the glass panels in place and extend peripherally around both the inside and outside glass surfaces of the doors. The door rails are fastened together at mitered corners of upper and lower horizontal rail members and left and right vertical side members. The hardware for connecting the corners of the rail structures also can be complicated, with their own significant number of inter-fitting parts for a suitable corner connection. Hinge elements support the door for pivoting movement relative to a vertical axis.
Extruded aluminum rail members may provide an aesthetically pleasing appearance, but are limited in terms of color and texture. While extruded aluminum elements may be formed with different profiles, a large number of frame profiles would require a significant inventory of parts.
The metal frame and door rail members, while providing suitable structural support and pleasing aesthetic appearance, readily conduct heat from outside the refrigerated display case, as well as serving as a condensation surface for water vapor which may be present in the ambient air. To reduce condensation and fogging, heater wires are sometimes placed in the frame and door rails to warm the rails and to thus inhibit condensation, especially in freezer cases. However, the consumption of energy by the heater wires adds an annual cost to the operation of the display case.
Frames, mullions and doors are described for refrigerated display cases having one or more aspects which contribute to improved thermal efficiency, energy savings or lower manufacturing costs. In one aspect of these inventions, a display case can meet or exceed one or more thermal performance standards set by a standards association. Greater flexibility and simplicity in the manufacturing process may also result from one or more aspects of these inventions.
In accordance with one aspect of one of the present inventions, a frame is provided for a refrigerated display case having a number of walls formed from cold rolled steel. The walls can be formed as an integral unit or separately and later brought together to form the frame. A steel frame has lower thermal conductivity than extruded aluminum, and provides a frame with improved thermal efficiency as well as improved energy efficiency. A steel frame can also reduce the cost of the display case when considering present-day costs of extruded aluminum. A steel framing can also improve the tolerances allowed in manufacturing and assembly, and can improve the form, fit and function of the display case.
In accordance with another aspect of one of the present inventions, a method is provided for forming a frame, such as a perimeter frame, mullions or door frame, which processes part of the frame prior to forming the frame element. For example, formation of mounting holes, hardware attachment points or other processing can be carried out before the frame element is formed into its final cross-sectional shape. As a result, different elements of a frame can be passed through the same forming or bending process without regard to whether the frame element is a top or bottom frame rail having mounting holes for hinge elements and hold-opens, or side frame rails having only openings for corner fasteners, or the like. The ability to process the frame elements in different ways provides more flexibility in the manufacturing process, and may result in lower overall costs with a lower rejection rate.
In the context of a perimeter frame, a frame for an opening in a refrigerated display case may include a first wall extending rearwardly, a second wall extending from the first wall in a second direction and a third wall extending from the second wall in a direction different from the second direction to define a recess between the first, second and third walls. A contact plate extends between the first and third walls closing the recess. The first, second and third walls are preferably formed from rolled steel and at least one of the walls includes a bend, for example for strength, to receive part of another component, or to hide an edge. In one preferred embodiment, each wall is substantially perpendicular to its adjacent wall. In another preferred embodiment, the contact plate includes a backing or carrier plate or mounting assembly that may carry the contact plate and that also may further insulate the contact plate from possible thermal transfer between the metal of the frame and the contact plate.
In accordance with a further aspect of one of the present inventions, a frame for an opening in a refrigerated display case may include first, second and third walls formed from rolled steel or stamped or other formed steel, and insulation to reduce thermal transfer from one side of the frame to the other. For example, the insulation may be provided in strips or sheets applied to the cold side of the frame, foamed or sprayed on, or applied as a blanket or in other ways. Insulation may improve the thermal and energy characteristics of the frame in many situations. Insulation may also be provided in the form of one or more air pockets created when a plastic or other cover is applied to the cold side of the frame. The plastic cover may include spacers, standoffs or other structures to keep most of the cover spaced from the surface of the frame, thereby providing the desired air pockets. Air flow within the pocket or pockets is preferably minimized. The cover may also be used to help in holding one or more components in place, such as contact plates, for example using zipper strips, snap features or similar devices.
In accordance with another aspect of one of the present inventions, the frame may be a door frame for surrounding or supporting a glass unit. The door frame is formed from rolled steel or stamped steel and includes a forward portion extending inwardly from a perimeter frame edge portion toward an edge of the forward glass pane and a first side portion extending rearwardly to a second wall, which in turn includes a third wall defining a groove. A plastic or other insulating element extends over part of the second wall to insulate the second wall. In one preferred embodiment, the insulating element keeps the steel from coming into direct contact with the cold of the refrigerated display case. For example, the insulating element may extend the complete distance from the metal door frame and contact a surface of the rear most glass pane. The door may also include additional insulation to further improve the thermal efficiency.
In accordance with further aspects of the door frame, the rolled or stamped steel may include rolled-back edges to hide raw, cut edges. In another embodiment, the frame includes a further wall extending in the front-to-back direction and which, at least partly, helps to define a seat or back stop for the glass unit. The further wall may be exposed to direct contact with a glazing channel about the glass unit, or a portion of the insulating element may be inter-posed between the further wall and the glazing channel. In another embodiment, the insulating element may include a receptacle, groove or other means for receiving and retaining a sealing gasket. The sealing gasket may help to insulate the frame from the cold. While parts of the sealing gasket are preferably flexible, the insulating element is preferably substantially rigid plastic. In an additional embodiment, the rolled steel frame may include a groove, channel or other opening in a perimeter surface, such as a rear perimeter surface, for receiving part of the insulating element.
The door frame in accordance with one aspect of the present inventions can be configured as a drop in door assembly, and may include an opening in the metal frame directed toward the edges of the glass or the perimeter edge of the glass unit. In another configuration of a drop in unit, the rearward facing portion of the frame may be closed, or may include a wall which omits any opening toward the rear portion of the door. In a door frame configured as a pound-on assembly, the metal frame element may include a forward wall extending over part of a forward glass pane and a rearward wall extending over part of a rearward glass pane where the forward and rearward walls extend different lengths, the forward preferably more than the rearward wall. In another form, the sealing gasket preferably extends inwardly over the metal door rail sufficient to contact the rearward glass pane.
In a further form of the present inventions, a mullion is formed from rolled steel, and may include insulation to insulate the mullion from the cold of the case. The insulation may be applied as a blanket, with an adhesive or as air pockets created by positioning or attachment of a mullion cover or similar structure.